Resistive heater coatings for dishwashing appliances

ABSTRACT

A dishwashing appliance may generally include a door and a tub defining a wash chamber configured to be closed via the door. The tub may include a top wall, a bottom wall and sidewalls extending between the top and bottom walls. In addition, the dishwashing appliance may include a heating device provided in operative association with the tub. The heating device may correspond to a resistive coating applied directly onto a surface of the bottom wall of the tub, wherein, when current is supplied through the resistive coating, the heating device is configured to generate heat.

FIELD OF THE INVENTION

The present subject matter relates generally to dishwashing appliances and, more particularly, to a resistive coating for heating the interior of a tub of a dishwashing appliance.

BACKGROUND OF THE INVENTION

Modern dishwashers typically include a tub defining a wash chamber where e.g., detergent, water, and heat can be applied to clean food or other materials from dishes and other articles being washed. Various cycles may be included as part of the overall cleaning process. For example, a typical, user-selected cleaning option may include a wash cycle and rinse cycle (referred to collectively as a wet cycle), as well as a drying cycle. A pre-wash cycle may also be included as part of the wet cycle, and may be automatic or an option for particularly soiled dishes.

It is common to provide dishwashers with rod-type, resistive heating elements in order to supply heat within the wash chamber during one or more of the dishwasher cycles (e.g., during the drying cycle). Such rod-type resistive heating elements are generally commercially available, such as the type sold under the name CALROD. Generally, these heating elements include an electric resistance-type wire that is encased in a ceramic-filled, metallic sheath. The wire/sheath assembly is then mounted at the bottom of the wash chamber at a location spaced apart from the bottom wall of the dishwasher tub. As a result, conventional heating elements typically take up valuable space within the wash chamber. Moreover, such heating elements are typically not very aesthetically pleasing.

Accordingly, an improved heating device for a dishwashing appliance that frees up space within the wash chamber and/or that provides for a more aesthetically pleasing look would be welcomed in the technology.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one aspect, the present subject matter is directed to a dishwashing appliance including a door and a tub defining a wash chamber configured to be closed via the door. The tub may include a top wall, a bottom wall and sidewalls extending between the top and bottom walls. In addition, the dishwashing appliance may include a heating device provided in operative association with the tub. The heating device may correspond to a resistive coating applied directly onto a surface of the bottom wall of the tub, wherein, when current is supplied through the resistive coating, the heating device is configured to generate heat.

In another aspect, the present subject matter is directed to a tub for a dishwashing appliance. The tub may generally include a wash chamber defined at least partially by a top wall, a bottom wall and sidewalls extending between the top and bottom walls. In addition, the tub may include a heating device provided in operative association the bottom wall. The heating device may correspond to a resistive coating applied directly onto a surface of the bottom wall, wherein, when current is supplied through the resistive coating, the heating device is configured to generate heat.

In a further aspect, the present subject matter is directed to a dishwashing appliance including a door and a tub defining a wash chamber configured to be closed via the door. The tub may include a top wall, a bottom wall and sidewalls extending between the top and bottom walls. In addition, the dishwashing appliance may include a heating device provided in operative association with the tub. The heating device may correspond to a resistive coating applied directly onto a surface of at least one of the top wall, the bottom wall or one of the sidewalls of the tub, wherein, when current is supplied through the resistive coating, the heating device is configured to generate heat.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 illustrates a front view of one embodiment of a dishwashing appliance in accordance with aspects of the present subject matter;

FIG. 2 illustrates a cross-sectional side view of the dishwashing appliance shown in FIG. 1, particularly illustrating various internal components of the dishwashing appliance.

FIG. 3 illustrates a front perspective view of a lower portion of the wash chamber defined by the tub of the dishwashing appliance shown in FIGS. 1 and 2, particularly illustrating one embodiment of a heating device provided in operative association with a bottom wall of the tub;

FIG. 4 illustrates a cross-sectional view of the tub shown in FIG. 3 taken at line 4-4, particularly illustrating the heating device as a resistive coating applied to an outer surface of the bottom wall of the tub;

FIG. 5 illustrates a similar front perspective view to that shown in FIG. 3, particularly illustrating another embodiment of a heating device provided in operative association with the bottom wall of the tub; and

FIG. 6 illustrates a cross-sectional view of the tub shown in FIG. 5 taken at line 6-6, particularly illustrating the heating device as a resistive coating applied to an inner surface of the bottom wall of the tub.

DETAILED DESCRIPTION OF THE INVENTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

In general, the present subject matter is directed to an improved heating device for a dishwashing appliance. Specifically, in several embodiments, the heating device may correspond to a resistive coating configured to be applied to one of the walls of the dishwasher tub. For example, as will be described below, a resistive coating may be applied to an outer surface and/or an inner surface of the bottom wall of the dishwasher tub. By supplying an electrical current through the resistive coating, the heating device may provide heating within the wash chamber, which may allow for desired dishwasher performance.

It should be appreciated that, by applying the resistive coating to an outer surface of the dishwasher tub, the disclosed heating device may not occupy any of the limited space within the wash chamber. In addition, such a configuration may allow for the heating device to be hidden from view, thereby providing the wash chamber with a more aesthetically pleasing look.

Moreover, even when the resistive coasting is applied to an inner surface of the dishwasher tub, the heating device may occupy a minimal amount of space within the wash chamber due to its low profile, thereby freeing up considerably more space than what would otherwise be available using a conventional rod-type resistive heating element. Further, by applying the internal heating device to the inner surface of the tub according to a selected pattern, the heating device, itself, may provide a unique look to the interior of the wash chamber.

Referring now to the drawings, FIGS. 1 and 2 illustrate one embodiment of a domestic dishwashing appliance 100 that may be configured in accordance with aspects of the present disclosure. As shown in FIGS. 1 and 2, the dishwashing appliance 100 may include a cabinet 102 having a tub 104 therein defining a wash chamber 106. The tub 104 may generally include a front opening (not shown) and a door 108 hinged at its bottom 110 for movement between a normally closed vertical position (shown in FIGS. 1 and 2), wherein the wash chamber 106 is sealed shut for washing operation, and a horizontal open position for loading and unloading of articles from the dishwasher. As shown in FIG. 1, a latch 112 may be used to lock and unlock the door 108 for access to the chamber 106.

As is understood, the tub 104 may generally have a rectangular cross-section defined by various wall panels or walls. For example, as shown in FIG. 2, the tub 104 may include a top wall 160 and a bottom wall 162 spaced apart from one another along a vertical direction V of the dishwashing appliance 100. Additionally, the tub 104 may include a plurality of sidewalls 164 (e.g., four sidewalls) extending between the top and bottom walls 160, 162. It should be appreciated that the tub 104 may generally be formed from any suitable material. However, in several embodiments, the tub 104 may be formed from a ferritic material, such as stainless steel.

As particularly shown in FIG. 2, upper and lower guide rails 114, 116 may be mounted on opposing side walls 164 of the tub 104 and may be configured to accommodate roller-equipped rack assemblies 120 and 122. Each of the rack assemblies 120, 122 may be fabricated into lattice structures including a plurality of elongated members 124 (for clarity of illustration, not all elongated members making up assemblies 120 and 122 are shown in FIG. 2). Additionally, each rack 120, 122 may be adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside the wash chamber 106, and a retracted position (shown in FIGS. 1 and 2) in which the rack is located inside the wash chamber 106. This may be facilitated by rollers 126 and 128, for example, mounted onto racks 120 and 122, respectively. As is generally understood, a silverware basket (not shown) may be removably attached to rack assembly 122 for placement of silverware, utensils, and the like, that are otherwise too small to be accommodated by the racks 120, 122.

Additionally, the dishwashing appliance 100 may also include a lower spray-arm assembly 130 that is configured to be rotatably mounted within a lower region 132 of the wash chamber 106 directly above the bottom wall 162 of the tub 104 so as to rotate in relatively close proximity to the rack assembly 122. As shown in FIG. 2, a mid-level spray-arm assembly 136 may be located in an upper region of the wash chamber 106, such as by being located in close proximity to the upper rack 120. Moreover, an upper spray assembly 138 may be located above the upper rack 120.

As is generally understood, the lower and mid-level spray-arm assemblies 130, 136 and the upper spray assembly 138 may generally form part of a fluid circulation assembly 140 for circulating water and dishwasher fluid within the tub 104. As shown in FIG. 2, the fluid circulation assembly 140 may also include a pump 142 located in a machinery compartment 144 located below the bottom wall 162 of the tub 104, as is generally recognized in the art. Additionally, each spray-arm assembly 130, 136 may include an arrangement of discharge ports or orifices for directing washing liquid onto dishes or other articles located in rack assemblies 120 and 122, which may provide a rotational force by virtue of washing fluid flowing through the discharge ports. The resultant rotation of the lower spray-arm assembly 130 provides coverage of dishes and other dishwasher contents with a washing spray.

The dishwashing appliance 100 may be further equipped with a controller 146 configured to regulate operation of the dishwasher 100. The controller 146 may generally include one or more memory devices and one or more microprocessors, such as one or more general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with a cleaning cycle. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor.

The controller 146 may be positioned in a variety of locations throughout dishwashing appliance 100. In the illustrated embodiment, the controller 146 is located within a control panel area 148 of the door 108, as shown in FIG. 1. In such an embodiment, input/output (“I/O”) signals may be routed between the control system and various operational components of dishwashing appliance 100 along wiring harnesses that may be routed through the bottom 110 of the door 108. Typically, the controller 146 includes a user interface panel/controls 150 through which a user may select various operational features and modes and monitor progress of the dishwasher 100. In one embodiment, the user interface 150 may represent a general purpose I/O (“GPIO”) device or functional block. Additionally, the user interface 150 may include input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface 150 may also include a display component, such as a digital or analog display device designed to provide operational feedback to a user. As is generally understood, the user interface 150 may be in communication with the controller 146 via one or more signal lines or shared communication busses.

Additionally, as shown in FIG. 2, a portion of the bottom wall 162 of the tub 104 may be configured as a tub sump portion 152 that accommodates a filter assembly 154 configured to remove particulates from the fluid being recirculated through the wash chamber 106 during operation of the dishwashing appliance 100. For example, fluid collected within the tub sump portion 152 of the bottom wall 162 may be passed through the filter assembly 154 and then diverted back to the pump 142 for return to the wash chamber 106 by way of the fluid recirculation assembly 140.

Moreover, as shown in FIG. 2, the dishwashing appliance 100 may also include a heating device 200 provided in operative association with the tub 104 for providing heat energy during a wash, rinse, and/or drying cycle to, for example, heat the fluid introduced into wash chamber 106 and/or to assist with drying articles. As will be described in greater detail below, the heating device 200 may generally correspond to a resistive coating configured to be applied directly to a wall of the tub 104, such as the bottom wall 162.

It should be appreciated that the present subject matter is not limited to any particular style, model, or configuration of dishwashing appliance. The exemplary embodiment depicted in FIGS. 1 and 2 is simply provided for illustrative purposes only. For example, different locations may be provided for the user interface 150, different configurations may be provided for the racks 120, 122, and other differences may be applied as well.

Referring now to FIGS. 3 and 4, one embodiment of a suitable configuration for the heating device 200 described above is illustrated in accordance with aspects of the present subject matter. Specifically, FIG. 3 illustrates a partial, front perspective view of the interior of the tub 104, particularly illustrating the lower region 132 of the wash chamber 106 generally adjacent to the bottom wall 162 of the tub 104. Additionally, FIG. 4 illustrates a cross-sectional view of a portion of the bottom wall 162 of the tub 104 taken about line 4-4 in FIG. 3.

As shown in FIGS. 3 and 4, the disclosed heating device 200 may be provided in operative association with the tub 104 for heating the wash chamber 106 and/or the fluid contained within the wash chamber 106. As indicated above, in several embodiments, the heating device 200 may correspond to a resistive coating 202 configured to be applied to a surface of one of the walls of the tub 104. For example, in the illustrated embodiment, the heating device 200 corresponds to a resistive coating 200 that has been applied to an exterior or outer surface 204 of the bottom wall 162 of the tub 104 (as opposed to an interior or inner surface 206 of the bottom wall 162). By positioning the heating device 200 on the outer surface 204 of bottom wall 162, the heating device 200 may be hidden when viewing the interior of the tub 104, (e.g., as indicated by the hidden lines in FIG. 3). In such instance, the heat generated by the heating device 200 may be directed through the bottom wall 162 of the tub 104 (e.g., via conduction and/or radiation) and into the wash chamber 106 to provide desired heating within the chamber 106 (e.g., during the drying cycle).

In general, the resistive coating 202 may be formed using any suitable resistive material that generates heat energy when an electrical current is transmitted therethrough. For example, suitable resistive heating materials may include, but are not limited to, certain ceramic materials (e.g., aluminum oxide and chromium oxide), aluminum, copper, carbon, steel alloys and/or any combinations thereof. Moreover, in a particular embodiment, the resistive coating 202 may be formed from a resistive ink and/or paste. For example, suitable resistive inks and/or pastes that may be used to form the resistive coating 202 may include, but are not limited to, carbon-based, silver-based, copper-based and/or conductive polymer-based inks and/or pastes.

It should be appreciated that the resistive coating 202 may be applied to the surface of the bottom wall 162 using any suitable application process and/or methodology known in the art. For example, in one embodiment, the resistive coating 202 may be applied on the bottom wall 162 using a 3-D printing process and/or any other suitable additive manufacturing process. In such an embodiment, it may be desirable for the resistive coating 202 to be made from a material suitable for deposition using such a process, such as a resistive ink and/or paste. Of course, in alternative embodiments, the resistive coating 200 may be applied using any other suitable application process.

It should also be appreciated that the resistive coating 202 may be applied onto the surface of the bottom wall 162 so as to define any suitable thickness or height 208 relative to the bottom wall 162. For example, as shown in FIG. 4, the height 208 of the resistive coating 202 may be defined as a dimension extending generally perpendicular to the surface of the bottom wall 162 at which the coating is applied. In several embodiments, the height 208 of the resistive coating 202 may range from about 0.0005 millimeters (mm) to about 10 mm, such as from about 0.001 mm to about 2.0 mm or from about 0.01 mm to about 1.0 mm and any other subranges therebetween.

Additionally, it should be appreciated that the resistive coating 202 may be applied onto the bottom wall 162 at any suitable location and/or may define any suitable shape and/or pattern along the wall 162 following application. For instance, in the illustrated embodiment, the resistive coating 202 has been applied onto the outer surface 204 of the bottom wall 162 so as to extend along a semi-circular path around the portion of the bottom wall 162 forming the tub sump portion 152 of the appliance 100. However, in other embodiments, the resistive coating 202 may be applied onto the surface 162 at any other suitable location and/or according to any other suitable pattern.

As indicated above, the heating device 200 may be configured to generate heat energy when an electrical current is directed through the resistive coating 202. Thus, as shown in FIG. 3, a power source 210 may be configured to be electrically coupled to the resistive coating 202. In general, the power source 210 may correspond to any suitable electrical device and/or component or other source of power that is configured to deliver an electrical current through the resistive coating 202, thereby allowing the heating device 200 to generate heat. For example, the power source 210 may simply correspond to the power source for the dishwashing appliance 100. Alternatively, the power source 210 may correspond to an electrical circuit or other component that is electrically coupled between the heating device 200 and the power source for the dishwashing appliance 100.

Referring now to FIGS. 5 and 6, another embodiment of a suitable configuration for a heating device 300 that may be utilized within the dishwashing appliance 100 described above with reference to FIGS. 1 and 2 is illustrated in accordance with aspects of the present subject matter. Specifically, FIG. 5 illustrates a partial, front perspective view of the interior of the tub 104, particularly illustrating the lower region 132 of the wash chamber 106 generally adjacent to the bottom wall 162 of the tub 104. Additionally, FIG. 6 illustrates a cross-sectional view of a portion of the bottom wall 162 of the tub 104 taken about line 6-6 in FIG. 5.

As shown, the heating device 300 may generally be configured the same as or similar to the heating device 200 described above with reference to FIGS. 3 and 4. For example, the heating device 300 may generally correspond to a resistive coating 302 configured to be applied to a surface of the bottom wall 162 of the tub 104 so as to define any suitable height 308 relative to the bottom wall 162, with the heating device 300 being electrically coupled to a suitable power source 210 for supplying an electrical current through the resistive coating 202. However, as shown in FIGS. 5 and 6, instead of being applied to the outer surface 204 of the bottom wall 162, the resistive coating 302 has been applied to the inner surface 206 of the bottom wall 162 such that the heating device 300 is directly exposed to the interior of the tub 104. As a result, the heating device 300 may be used to heat the wash chamber 106 defined within the tub 104 via radiation.

Additionally, as shown in FIG. 5, the resistive coating 302 has been applied to the bottom wall 162 of the tub 104 so as to define a different pattern or shape than the resistive coating 202 described above. Specifically, in the illustrated embodiment, the resistive coating 302 forms a serpentine-like pattern along the inner surface 206 of the bottom wall 162. Such a pattern may allow for heating device 300 to cover a larger area along the surface of the bottom wall 162, thereby allowing for a reduction in the power density across the heating device 300. However, as indicated above, the resistive coating 302 may, in other embodiments, be applied in any other suitable pattern and/or shape along the bottom wall 162.

It should be appreciated that, although the heating devices 200, 300 shown in FIGS. 3-6 have been described as separate embodiments, the heating device configurations disclosed herein may also be utilized in combination. For instance, in one embodiment, resistive coatings may be applied to both the outer surface 206 and the inner surface 204 of the bottom wall 162 such that heating devices are formed along both the exterior and the interior of the tub 104.

It should also be appreciated that, in general, the present subject matter has been described with reference to a heating device positioned on a surface of the bottom wall 162 of the tub 102. However, in other embodiments, the disclosed heating devices may be positioned along any other wall of the tub 104. For instance, in an alternative embodiment, the resisting coating(s) used to form the heating device(s) may be applied to the inner and/or outer surfaces of the sidewalls 164 and/or the top wall 160 of the tub 104.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. 

What is claimed is:
 1. A dishwashing appliance, comprising: a door; a tub defining a wash chamber configured to be closed via the door, the tub including a top wall, a bottom wall and sidewalls extending between the top and bottom walls; and a heating device provided in operative association with the tub, the heating device corresponding to a resistive coating applied directly onto a surface of the bottom wall of the tub, wherein, when current is supplied through the resistive coating, the heating device is configured to generate heat.
 2. The dishwashing appliance of claim 1, wherein the resistive coating is applied directly onto an outer surface of the bottom wall of the tub.
 3. The dishwashing appliance of claim 1, wherein the resistive coating is applied directly onto an inner surface of the bottom wall of the tub.
 4. The dishwashing appliance of claim 1, further comprising a power source electrically coupled to the heating device, the power source being configured to supply current to the heating device.
 5. The dishwashing appliance of claim 1, wherein the resistive coating is formed from at least one of a resistive ink or a resistive paste.
 6. The dishwashing appliance of claim 5, wherein the at least one of the resistive ink or the resistive paste is at least one of carbon-based, silver-based, copper-based or conductive-polymer based.
 7. The dishwashing appliance of claim 1, wherein the resistive coating is applied using a 3-D printing process.
 8. The dishwashing appliance of claim 1, wherein the tub is formed from stainless steel.
 9. The dishwashing appliance of claim 1, wherein, when current is supplied through the resistive coating, the heating device is configured to radiate heat through the bottom wall of the tub.
 10. The dishwashing appliance of claim 1, wherein the resistive coating is applied on the surface of the bottom wall along a semi-circular path.
 11. The dishwashing appliance of claim 1, wherein the resistive coating is applied on the surface of the bottom wall according to a pattern.
 12. A tub for a dishwashing appliance, the tub comprising: a wash chamber defined at least partially by a top wall, a bottom wall and sidewalls extending between the top and bottom walls; a heating device provided in operative association the bottom wall, the heating device corresponding to a resistive coating applied directly onto a surface of the bottom wall, wherein, when current is supplied through the resistive coating, the heating device is configured to generate heat.
 13. The tub of claim 12, wherein the resistive coating is applied directly onto an outer surface of the bottom wall.
 14. The tub of claim 12, wherein the resistive coating is applied directly onto an inner surface of the bottom wall.
 15. The tub of claim 12, wherein the resistive coating is formed from at least one of a resistive ink or a resistive paste.
 16. The tub of claim 15, wherein the at least one of the resistive ink or the resistive paste is at least one of carbon-based, silver-based, copper-based or conductive-polymer based.
 17. The tub of claim 12, wherein the resistive coating is applied using a 3-D printing process.
 18. The tub of claim 12, wherein the resistive coating is applied on the surface of the bottom wall along a semi-circular path.
 19. The tub of claim 12, wherein the resistive coating is applied on the surface of the bottom wall according to a pattern.
 20. A dishwashing appliance, comprising: a door; a tub defining a wash chamber configured to be closed via the door, the tub including a top wall, a bottom wall and sidewalls extending between the top and bottom walls; and a heating device provided in operative association with the tub, the heating device corresponding to a resistive coating applied directly onto a surface of at least one of the top wall, the bottom wall or one of the sidewalls of the tub, wherein, when current is supplied through the resistive coating, the heating device is configured to generate heat. 